In cutting or sawing of pieces of wood and the like, such as sheets of plywood, it is often difficult to achieve a straight cut parallel to an edge of the sheet due to improper alignment of a line to be cut along or a straight edge to be used as a guide between the end of the sheet or board. This results in unsatisfactory material to be used in construction or repair work and frequently results in scrap material. This can naturally result in increased cost of construction and repair and it is therefore highly desirable to be able to make the desired cut without loss of material resulting in scrap, and to which the present invention is directed. Before every cut is made a time consuming mathematical calculation must be made to determine where to clamp the straight edge that guides the saw and any error in such calculation will result in more wasted material.